1. Field of the Invention
The present invention relates to a quadruple frequency converter using a synchronous rotating machine.
2. Description of the Prior Art
Frequency converters for obtaining quadruple frequency of a source frequency are known. One such known frequency converter is a static type frequency converter using semiconductor devices. Also, a rotating machine type frequency converter based on the principle of a motor-generator is known. The latter type, i.e., the rotating machine type is suitable as an electric source for high speed motors of small capacity used in the construction field or the like by the reason of its low cost and robustness.
The conventional rotating type frequency converters are mainly of the motor-generator type, in which an ac generator is driven by an ac motor. This type requires two rotating machines so that it generally becomes costly and troublesome to maintain due to the presence of slip rings and brushes, which tend to wear and cause trouble.